Persons that enter a hoistway, such as elevator mechanics, building maintenance personnel, and unauthorized persons such as vandals, may suffer serious and fatal accidents when the elevator moves unexpectedly at normal speed. Such accidents most commonly occur in the overhead or the pit where the person is crushed by the sudden movement of the elevator. This problem is aggravated in systems in which the hoisting machine and/or the controller are located in the pit. As architects continue to try to reduce the size of the overhead and the depth of the pit, the problem becomes even worse.
Heretofore, elevator systems have not made provision to recognize when persons have entered the hoistway, relying instead on the mechanic moving an inspection switch from the normal mode of operation position to the inspection mode of operation position. This is typically achieved when the elevator is parked at one floor, the mechanic forces the hoistway doors open on the next higher floor, the mechanic thereupon enters the hoistway on the roof of the cab, and usually transfers the inspection switch from the normal mode of operation to the inspection mode of operation, and then controls the motion of the cab by means of switches on the inspection box. When the mechanic returns the maintenance switch to the normal mode of operation, the hoistway door switch may be shorted out or defective so it appears that the safety chain is made, or if the mechanic failed to put the inspection switch into the inspection mode, the elevator may start up for some reason, which has resulted in crushing the mechanic between the top of a car and the sill of the hoistway door.
A partial solution to this known to the prior art is requiring a sequence including that a hoistway door shows as being open, followed by the stop switch being in the stop position, then the inspection switch being transferred to normal, and then the hoistway doors all being closed. However, this still does not inform the system when someone has entered the hoistway in the first place, which is still only learned when the inspection switch is transferred to the inspection mode, whereby any mechanics within the hoistway are at risk of being crushed. Furthermore, none of these systems detect the case when the mechanic enters the pit (where he cannot activate the inspection switch).